Burglar and fire alarm



Feb. 16, 1932.

A R. MORRISON BURGLAR AND FIRE ALARM Filed Oct. 12 1926 mmm mum Patented Feb. 16, 1932 UNITE ALAN RAYMOND Monaisoiv,

OF SPOKANE, WASHINGTON BURGLAR AND FIRE ALARM Application filed October 12,

'10 one of which is controlled by the service or line circuit, and the other of which is controlled by an independent circuit including the protective medium, the arrangement being such'that on failure of the source of currentone of the breaks in the alarm circuit is closed, but the other of such breaks is immediately opened, whereby the alarm circuit isprevented from operating until the protective medium is ruptured.

A further object is the provision of an alarm element constructed to control a switch arranged in the line circuit so that as long as the alarm is sounding the line circuit is broken whereby to render it impossible to 25 interrupt the alarm by restoring the rupture of the protective medium.

A further object is the provision of an element in the alarm proper which, if broken, in an attempt to stop the alarm through manipulation of the latter, the line switch will be opened or held open to prevent interrupting of the alarm circuit.

The invention is illustrated in the accompanying drawings in which:

Fig. 1' is a diagrammatic view illustrating the improved alarm.

Fig. 2 is a section on line 2-2 of Fig. 1.

'The improved alarm system comprises an alarm proper, here shown in the form of a motor driven siren 1, the motor of which is energized from a battery 2 through a circuit including conductors 3 and 4 controlled through a manually operable switch 5. The circuit wire indicated at 6, hereinafter referred to as the protective medium, is to be 1926. Serial No. 141,189.

arranged throughout or within the area to be protected so that any unauthorized attempt in connection with such will result in a rupture of this protective medium, which rupture will of course, follow the action of] fire. terminals 7 of the protective medium are secured to the terminals of line service conductors 8 and 9, which conductors are designed to be energized from the city service and may, and preferablydo, include a resistance 10 to reduce the voltage. The conductor 9 which, together with conductor 8, forms what will be hereinafter termed the line service, leads through the switch 5'.

The protective medium 6 also includes what i may be termed an auxiliary switch circuit including a source of energy, as a battery 12, a conductor 13 leading from one side thereof, and connected to the service line 8 and a conductor 14 which leads to and is connected to the conductor 3 of the alarm circuit proper as at 15. The conductor 3 between the point 15 and the switch 5 is therefore common to the alarm circuit proper and the auxiliary switch circuit. v

That portion of the conductor 3 which is common to the alarm circuit proper and the auxiliary switch circuit is provided with independent breaks 16 and 17 adapted to be bridged or closed by the cores 18 and 19 of solenoids 20 and 21 respectively. The solenoid 20'is in series in conductor 9 of the line circuit, and the solenoid 21 is bridged across the lineconductor 9 and the conductor 3 by the conductors 22, 28.

Obviously, both breaks or interruptions'in the alarm circuit proper must be closed in order to permit the alarm to sound, and in order that such breaks should be closed both solenoids 20 and 21 must be de-energized.

The line conductor 9' beyond the solenoids 20 and 21, is in series connection through conductors 83 and 34 with a switchll, arranged adjacent the siren 1.

The switch 11 in the conductor 9'includes 5 The Q a contact 24 and an angle lever 25 pivotally mounted at 26 and carrying a contact 2?, to cooperate with the contact 24. The contact 24 and the pivotal support of the angle lever form the terminals of the conductors 33 and 34 forming part of the line conductor 9. The motor of the siren drives the usual rotating element to produce the sound, and the air drawn through the horn by this rotating element is forced upwardly through openings 28 in the outer wall of the annular chamber 29 surrounding the rotor, with the air currents thus directed impinging against a plate 30 carried by the angle lever between the pivot 26 and contact 27 so that while the siren is operating the line conductor 9 and thus the line service, is interrupted at the switch 11, which switch in itself holds both solenoids 20 and 21 de-energized.

The angle lever 26 includes an arm 31 which depends through a slot in the wall of the siren and in rear of the screen 32 arranged within the horn of the siren. If any attempt is made to mutilate the siren through the horn in order to stop the alarm, the pressure will indent or rupture the screen 32 with the eifect to move the arm 31 rearwardly and thus of itself open the switch 11.

Assuming the parts constructed and arranged as described, the protective medium 6 intact, with current flowing from the line service, it will be apparent that solenoid 20 is thereby energized and core 18 thereof withdrawn to maintain the break 16 open. This interrupts the alarm circuit proper, and the alarm is silent. Any interruption of the line circuit, as for example by rupturing the protective medium, or displacing the screen to render the siren inoperative, will de-energize the solenoid 20, permit the core thereof to drop, and close the break 16, whereupon the alarm circuit proper is completed and the alarm sounds. If this interruption of the line circuit has resulted from rupture of the protective medium 6, it will be apparent that the completion of this protective medium following its rupture will not result in a cessation of this siren, for immediately the siren sounds, the switch 11 is opened by the air currents against the plate 30, so that if the integrity of the protective medium is restored, the line circuit is still broken through the switch 11, and the solenoids 20 and 21 remain de-energized. It is to be noted that the batteries 2 and 12 are of the same strength and connected in opposition. This prevents a closed circuit which would otherwise tend to operate the horn intermittently.

It not infrequently happens in alarms of this character that a failure of the line circuit, that is an interruption of the city service will result in the sounding of the alarm when there is in reality no occasion for such alarm. To overcome this fault, the auxiliary switch circuit has been provided. It is noted that this circuit includes the protective medium, the battery 12, the solenoid 21, and the switch 5, and that if the line service fails, and the solenoid 20 becomes de-energized to permit its core 18 to close the break 16, the auxiliary alarm circuit, immediately the break 16 is closed, becomes energized from the battery 12, with the result that the solenoid 21 is energized and break 17 opened, so that the alarm circuit proper is still interrupted, notwithstanding the failure of the line service. Even under these conditions, where the auxiliary switch circuit is controlling the alarm circuit proper, through the solenoid 21, any rupture of the protective medium 6 immediately deenergizes the solenoid 21, and permits the core 19 thereof to close the break 17 in the alarm circuit proper to sound the alarm.

It is to be particularly noted that after the alarm has started sounding, it cannot be interrupted except through operation of the switch 5.

The switch solenoids indicate conventionally any electrically operated switch control means and the switch 5 may be of any usual or conventional form so long as it will simultaneously control one of the line service conductors and a conductor of the alarm circuit proper.

What is claimed as new is:

1. A burglar and fire alarm system including a line service circuit having a breakable conducting element for the area to be protected, an alarm, an alarm circuit including pairs of spaced contact points, an electro-magnetic switch energized by said line service circuit, said switch including means to close one pair of contact points upon failure of the line service circuit, a third circuit including the contacts controlled by said switch and the breakable conducting element, and a second electro-magnetic switch connected in the third. circuit normally closing the other pair of contacts in the alarm circuit upon failure of the line service circuit.

2. A burglar and fire alarm system including an alarm, an alarm circuit having a source of energy, a line service circuit including a breakable conducting element, a source of energy and the coil of a relay, an intermediary circuit including a source of electrical energy, the coil of a second relay and the breakable conducting element, contact means included in the first relay to close a gap in the alarm circuit and in the intermediary circuit when the first relay is de-energized, and contact means included in the second relay to close a second gap in the alarm circuit when the second relay is de-energized.

3. A burglar and fire alarm system including an alarm, an alarm circuit including a source of energy, a set of contacts breaking said alarm circuit, a second set of contacts breaking said alarm circuit, a line service Circuit including a breakable conducting element for the area to be protected, a solenoid in said line service circuit and actuated thereby, a core operated by said solenoid and adapted to bridge said first mentioned set of contacts upon failure of said line service circuit, an intermediate circuit including a source of energy, said first mentioned set of contacts of one alarm circuit and said breakable conducting element, a second solenoid actuated by said intermediate circuit, and a core operated by said second solenoid to bridge the second set of contacts in the alarm circuit, whereby said alarm circuit Will be operated only upon the breaking of the breakable conducting element.

In testimony whereof I affix my signature.

A. RAYMOND MORRISON. 

